1. Field of the Invention
The present invention relates to a method of electroplating capable of forming a column-shaped electrodeposit structure by using a photoresist over a seed layer, such as a conductive metal layer.
2. Description of the Prior Art
Electrodeposition or electroplating is one of the key technologies in the field of micromachining. A method of electroplating comprises a step of supplying electric current to a seed layer of conductive metal material in an electrolytic solution, so as to allow an electrodeposit to grow over the seed layer. When a predetermined pattern is defined on the seed layer by using a photoresist layer, for example, before the supply of electric current, an electrodeposit structure is allowed to grow over the seed layer at the exposed surface surrounded by the photoresist layer. The electrodeposit structure can be shaped into the predetermined pattern.
For example, when a column-shaped electrodeposit structure is intentionally formed by electroplating, a photoresist layer serves to define a column-shaped space by its wall surfaces upright to the seed layer. However, the column-shaped space hardly allows the electrolytic solution to enter the space, so that a bubble or bubbles tends to remain in the space. In addition, gas such as hydrogen generated in the electrolytic solution during supply of electric current cannot smoothly get out of the column-shaped space, either. Accordingly, the electrodeposit structure sometimes cannot grow enough over the seed layer within the column-shaped space because of interruption of the bubbles.